This invention relates to mats for use in vinyl sheet flooring.
In one of its more specific aspects, this invention pertains to an all glass mat of both textile and wool fibers which mat is used as an interlayer for compressible vinyl floor covering.
A vinyl floor covering is typically composed of a number of layers including a wear layer, a print/foam layer, a glass mat layer and a backing layer. The wear layer is typically polyurethane and provides the hard, abrasion-resistant surface required for good durability. The print/foam layer carries the decorative print and is chemically foamed and embossed. The glass mat layer is typically a 1.0 lb/100 ft.sup.2 mat produced with a suitable binder material. The backing layer is a vinyl film typically having the same mass as the print/foam layer. It may be solid or mechanically foamed and is present to completely encapsulate the glass mat as well as balance the construction of the vinyl floor covering.
All-glass flooring mat produced typically from 11 .mu.m.times.6 mm textile fiber has been used in Europe for some time in an interlayer construction in which the glass mat is located essentially in the center of the vinyl floor covering. Unlike the vinyl floor covering produced with felt backings (asbestos or otherwise), the symmetry of the interlayer construction provides a lay flat-stay flat flooring that does not have to be glued to the subfloor in order to provide a stable floor covering. In addition, the interlayer construction is very flexible which makes do-it-yourself installation readily possible.
However, an all-glass flooring mat has not been widely accepted in this country because of a difference in building construction techniques in the U.S. versus Europe. A very high percentage of European subfloors are concrete as opposed to the joist and plywood subfloor system employed in the United. States. The interlayer constructed vinyl floor covering is a very dimensionally stable product which is desirable from a manufacturing standpoint and with installations over concrete. However, the interlayer construction has been found not to be particularly desirable when the vinyl floor covering is installed over a wood subfloor due to the fairly large dimensional changes associated with wood as the temperature and humidity changes. As the subfloor "dries out" in the winter time, it can shrink by up to 0.5 percent. Unless the vinyl floor covering can accommodate this change in dimension through compression, the vinyl floor covering will buckle to relieve the compressive loading. The glass mats currently used in the interlayer construction for the vinyl floor covering are very stiff and have high compressive strengths which cna result in severe buckling of the floor covering when they are installed over wood subfloors.
Still, the use of glass mat for use as interlayers, for vinyl floor covering is well-known in the U.S. For example, the Bondoc, U.S. Pat. No. 4,269,886, discloses a mat which is produced of glass fibers ranging from 1/4 to 3 inches in length and 3 to 20 microns in diameter. However, this mat is only 3.9 mil. to 11.8 mil. in thickness and has voids throughout at least 20% of the surface. Generally, such mats are too dimensionally stable for use over wood subfloors. The dimensional stability of the vinyl floor covering is an important consideration not only when the floor covering is being installed by using a perimeter adhesion installation technique but also when an overall gluing technique is used as well. In addition, it is desirable for glass mats used as interlayers for vinyl floor covering to possess acceptable compressibility when saturated with a binder material. It is a current practice to mechanically score the backing layer of the vinyl floor covering in order to have a covering with acceptable compressibility. This final step of mechanically scoring the backing layer results in much wasting of the covering since the scoring is done, at times, either too deep or too shallow into the backing layer. Either way, the final product must be scrapped.
Another concern in producing a commercially acceptable compressible vinyl floor covering is that the glass mat used as the interlayer possess sufficient hot tensile strength such that the glass mat does not separate or fall apart during the various manufacturing steps of either the glass mat itself or the vinyl floor covering. In the production of glass mats no manufacturer has previously been able to achieve the desirable low rigidity of the glass mat without compromising the hot tensile strength of the glass mat. If the glass mat does not possess sufficient hot tensile strength, the glass mat will not be commercially processible in existing floor covering manufacturing processes.